Sand mold casting is a technique of making a sand mold by compacting powder such as green sand, and forming a casting using this sand mold. In making the sand mold, it is extremely important to check the presence or absence of powder in the powder filling process in order to stably make sand molds and reduce defects.
The green sand molding method in sand mold casting includes, for example, a sand filling process, that is, aeration by which green sand is blown in with compressed air, gravity filling, or blow by which sand is blown in to fill, and a subsequent process of compressing the filling green sand by mechanical squeeze. Green sand molds are made through these combined processes.
For example, when castings with a complex shape, such as engines, are to be obtained, the shape of the sand mold having the inverted shape of the casting is also complicated accordingly, and the filling of the complex-shaped part with green sand may be insufficient. In this case, sufficient sand mold strength may not be obtained by subsequent squeeze.
Since such defects in making a sand mold (for example, Patent Literature 1) cause casting defects, it is desired to prevent filling defects of casting molds in the previous process. For this purpose, simulation of molding sand filling defects (for example, Patent Literature 2) has been carried out, but in practice, no checking method by electrical means has been developed heretofore.